DC isn't exactly a shopper's paradise. There are only few areas with a noticeable concentration of good shops, such as M Street and Wisconsin Avenue in Georgetown and Connecticut Avenue from around Dupont Circle down. To really go shopping, it's best to go to Virginia, to the Fashion Mall in Pentagon City. It's a real American mall with fountains, a food court, a movie theatre, a couple of department stores and four floors of shops. Although the Fashion Mall focuses on clothing stores (mostly business and casual clothing for DC lawyers and lobbyists), there's also a separate mall on the other side of the metro station where you can find a big bookstore and electronics chain store. There's plenty to browse and some of it is actually quite affordable so you can easily spend there a whole day. Don't expect to find anything original, though, just a convenient concentration of the usual upscalish US stores.